1. Field Of The Invention
The present invention relates to a tool for servicing wells and more particularly to such a tool which is adaptable for use in wells of a variety of types to permit the injection of such fluids as acid, water, oil, cleansing agents and the like into a well and the formation laterally of the well for the purpose of maintaining the well by dissolving materials which clog and interfere with well operation as well as to clean, service and generally maintain all portions of a well casing and formation beyond the casing and to such a tool which can also be operated without removal from the well to extract such fluids from the well after use. While the present invention arose in connection with the servicing of wells and is conveniently described in connection with such use, it is to be understood that it may advantageously be employed in many other operational environments; such as boreholes, conduits, pipe lines, and the like and the term "wells" is intended to encompass such locations of use.
2. Description Of The Prior Art
In wells of all types, such as for oil, gas, water and the like, there is a propensity for minerals borne by the substance being recovered to become deposited on rock structures within the formation adjacent to the well, on the well casing and with apertures in the well casing through which such substances pass. Thus, over the period of use of the well it is necessary to utilize treating agents of a variety of types including acids, solvents, water and the like to treat the well casing, and the formation beyond the well casing for the removal of such deposited minerals so as to enhance the productivity of the well for continued use.
It has therefore been necessary to use several types of tools to inject such fluids into a well and to extract the fluids after use. In all of the conventional tools of which the applicant is aware, it is necessary to lower an appropriate tool into the well on the end of a pipe string composed of a multiplicity of endwardly interconnected pipe sections. Not infrequently, hundreds or even thousands of such pipe sections must be interconnected to reach the depths required. This, of course, requires that the pipe sections be interconnected as the tool is lowered into the well. Similarly, removal of the tool from the well requires the pipe sections to be disconnected as the tool is raised from the well. Such operations can require many days to complete. Furthermore, where the injected fluid is to be withdrawn from the well, as is normally the case, this process must be repeated at least a second time to permit the insertion of a second tool into the well for this purpose. In some instances, it is necessary or desirable to inject and extract several types of fluids sequentially into the well to accomplish the designed purpose. It will be seen that this necessitates the repetition of the interconnection and disconnection of the pipe sections for each type of fluid. The resultant expense, both as a function of man hours involved as well as of the "down time" during which the well is unproductive, places an extreme burden on the operation. The process can, in fact, prove to be prohibitively expensive where the effect of such maintenance is limited in duration.
Therefore, it has long been recognized that it would be desirable to have a tool for servicing wells useful in injecting fluids into and extracting fluids from a well which can simply be operated in sequence to inject into and extract from a well any number of fluids without removal of the tool from the well until the entire operation is completed and which is adaptable for use in wells of a variety of types, diameters, and depths.